Cumulonimbus calvus is a moderately tall

cumulonimbus cloud Cumulonimbus () is a dense, towering, vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. Above the lower portions of the cumulonimbus the water ...

that is capable of

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

but has not yet reached the

tropopause The tropopause is the atmospheric boundary that demarcates the lowest two layers of the atmosphere of Earth – the troposphere and stratosphere – which occurs approximately above the equatorial regions, and approximately above the polar regi ...

, which is the height of stratospheric stability at which cumulonimbus forms into cumulonimbus capillatus (fibrous-top) or

cumulonimbus incus A cumulonimbus incus (), also called an anvil cloud, is a cumulonimbus cloud that has reached the level of stratospheric stability and has formed the characteristic flat, anvil-shaped top. It signifies a thunderstorm in its mature stage, suc ...

(anvil-top). Cumulonimbus calvus develops from

cumulus congestus Cumulus congestus or towering cumulus clouds are a species of cumulus that can be based in the low- to middle-height ranges. They achieve considerable vertical development in areas of deep, moist convection. They are an intermediate stage between ...

, and its further development, under auspicious conditions, will result in

. This cloud consists mainly of water droplets. By definition of

, at its top water droplets are transformed into ice crystals. But for cumulonimbus calvus, content of ice crystals are meager and polar are in early stage, so the cloud tops still look round and puffy. Cumulonimbus Calvus at Lake Leaghur

Cumulonimbus calvus is categorized by size and development and lacks an anvil head found on Cumulonimbus capillatus or

Cumulonimbus incus A cumulonimbus incus (), also called an anvil cloud, is a cumulonimbus cloud that has reached the level of stratospheric stability and has formed the characteristic flat, anvil-shaped top. It signifies a thunderstorm in its mature stage, suc ...

. While lightning is not required, it can be used to differenciate it from Cumulus congestus. Developing cumulonimbus calvus lose sharp outlines of the top as more water droplets transform into ice crystals. Strong updrafts may form pileus or thin vertical stripes may protrude upwards out of the cloud. When upper parts of the cloud freeze to a greater extent and clearly visible cirriforms appear, cumulonimbus calvus metamorphoses into another species of

cumulonimbus Cumulonimbus () is a dense, towering, vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. Above the lower portions of the cumulonimbus the water va ...

Hazards

Like other cumulonimbus clouds, cumulonimbus calvus can cause severe weather conditions including: *

Lightning Lightning is a natural phenomenon consisting of electrostatic discharges occurring through the atmosphere between two electrically charged regions. One or both regions are within the atmosphere, with the second region sometimes occurring on ...

; these clouds can produce lightning. *

Wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...

; these clouds may produce strong winds especially during a

downburst In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. It originate ...

Hail Hail is a form of solid Precipitation (meteorology), precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailsto ...

; these clouds can sometimes produce hail *

Landspout __NOTOC__ Landspout is a term created by atmospheric scientist Howard B. Bluestein in 1985 for a tornado not associated with a mesocyclone. The ''Glossary of Meteorology'' defines a landspout as: Landspouts are typically weaker than mesocyc ...

; Cumulonimbus calvus clouds can, on rare occasions, produce a unique type of

tornado A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the ...

known as a landspout. Landspouts are formed when strong ground level rotation is caught in the updraft of the storm, pulling it upwards and connecting it to the clouds above resulting in the rotation becoming a true tornado. The cumulonimbus calvus can further grow larger if the updraft is strong. It can form into a

, and bring more severe thunderstorms that can cause constant cloud-to-ground lightning, extensive wind damage, microbursts, hail, and occasionally a

References

{{DEFAULTSORT:Cumulonimbus Calvus Cumulus